CD26, a 110 kDa cell surface glycoprotein, exhibits dipeptidyl peptidase IV (DPPIV; EC 3.4.14.5) enzyme activity and plays an important role in T cell co-stimulation. In the present study, the function of CD26/DPPIV in transendothelial migration was examined using β-chemokines as chemoattractants. When soluble recombinant CD26 (sCD26/DPPIV+) was added to the transendothelial chemotaxis system, chemotactic migration of T cells toward RANTES was significantly enhanced. Addition of sCD26 to 50 ng/ml of RANTES enhanced the migratory response by a factor of two compared to RANTES alone, whereas mutant soluble CD26 (mCD26), lacking the DPPIV enzyme activity, had no enhancing effect on RANTES-induced T cell migration. In the process of analyzing the mechanisms of the enhancement of T cell migration by sCD26, we showed that RANTES was cleaved by sCD26 under physiologic conditions at the precise site characteristic of its enzyme specificity. However, synthesized RANTES which lacks two N-terminal amino acids showed a chemotactic activity equivalent to full-length RANTES on T cells. Furthermore, addition of sCD26 showed enhancement of T cell migration induced by both forms of RANTES. In contrast to T cells, the truncated RANTES is inactive in chemotaxis of purified monocytes and supplement of sCD26 but not mCD26 reduced the migratory response of monocytes to RANTES. These results suggest that CD26/DPPIV differentially regulate the chemotactic response of T cells and monocytes to RANTES.
Objective To investigate the novel antiinflammatory mechanism of a disease-modifying antirheumatic drug, bucillamine, on activated T cells, specifically its effect on T cell proliferation, cytokine production, and migration of T cells. Methods T cells were cultured in wells coated with anti-CD3 monoclonal antibodies (mAb) plus anti-CD26 mAb or anti-CD3 plus anti-CD28 mAb, with or without bucillamine. Proliferative responses and the production of interleukin-2 (IL-2), interferon-γ (IFNγ), tumor necrosis factor α (TNFα), IL-6, IL-4, and IL-5 were measured under these costimulatory conditions. Phytohemagglutinin (PHA)–activated T cells were cultured on human umbilical vein endothelial cell–coated transwells in the presence or absence of bucillamine, and T cells migrating through the endothelial cell layer were counted. Immunofluorescence analysis was also performed to analyze the effect of bucillamine on the surface expression of adhesion molecules on T cells. Results Bucillamine (64 μM) significantly inhibited T cell proliferation and the production of IL-2, IFNγ, TNFα, and IL-6, whereas it had no inhibitory effects on the production of IL-4 and IL-5 in the cultures with anti-CD3 plus anti-CD26 mAb. In contrast, bucillamine had no effects on T cell proliferation or any cytokine production in the cultures with anti-CD3 plus anti-CD28 mAb. Furthermore, the same concentration of bucillamine inhibited transendothelial migration of PHA-activated T cells, and reduced the expression level of CD44 on T cells. Conclusion This study demonstrated the novel effects of bucillamine in vitro, showing inhibition of type 1 T helper–type cytokine production and proinflammatory cytokine production induced by certain costimulatory conditions, and inhibition of transendothelial migration of T cells. The inhibition of T cell migration appeared to be mediated partly through the reduced expression of CD44, an adhesion molecule on the T cell surface.
Stanniocalcin is a glycoprotein hormone that regulates the calcium level in fish. We found that mRNA of human stanniocalcin 1 (STC-1) is detectable in phytohemagglutinin-stimulated T cells and in most human leukemia cell lines, suggesting a role of STC-1 for cell proliferation. This finding prompts us to study the usefulness of STC-1 for monitoring acute leukemia. The levels of STC-1 transcripts increased in patients with acute leukemia at diagnosis and relapse, as judged by quantitative real-time RT-PCR. Levels of transcripts rapidly decreased to within the cut-off levels, when the blast numbers decreased with chemotherapy. Prolonged elevation of STC-1 levels after treatment was associated with a poor prognosis. All of 7 patients relapsed 1 to 4 months after they showed an elevated level of the transcripts in clinical remission. These results indicate that STC-1 is a novel marker for minimal residual disease of acute leukemia, and for an early diagnosis of relapse.
ABSTRACT Carotid intimal-medial thickening was observed in a 23-year-old woman with acute cytomegalovirus (CMV) infection. The thickening disappeared after her recovery from the infection. As endothelial cells are common targets of CMV, this thickening suggests that CMV infection causes vascular lesions, even in otherwise healthy individuals.
CD26 is a T cell activation antigen known to bind adenosine deaminase and have dipeptidyl peptidase IV activity. Cross-linking of CD26 and CD3 with immobilized mAbs can deliver a costimulatory signal that contributes to T cell activation. Our earlier studies revealed that cross-linking of CD26 induces its internalization, the phosphorylation of a number of proteins involved in the signaling pathway, and subsequent T cell proliferation. Although these findings suggest the importance of internalization in the function of CD26, CD26 has only 6 aa residues in its cytoplasmic region with no known motif for endocytosis. In the present study, we have identified the mannose 6-phosphate/insulin-like growth factor II receptor (M6P/IGFIIR) as a binding protein for CD26 and that mannose 6-phosphate (M6P) residues in the carbohydrate moiety of CD26 are critical for this binding. Activation of peripheral blood T cells results in the mannose 6 phosphorylation of CD26. In addition, the cross-linking of CD26 with an anti-CD26 antibody induces not only capping and internalization of CD26 but also colocalization of CD26 with M6P/IGFIIR. Finally, both internalization of CD26 and the T cell proliferative response induced by CD26-mediated costimulation were inhibited by the addition of M6P, but not by glucose 6-phosphate or mannose 1-phosphate. These results indicate that internalization of CD26 after cross-linking is mediated in part by M6P/IGFIIR and that the interaction between mannose 6-phosphorylated CD26 and M6P/IGFIIR may play an important role in CD26-mediated T cell costimulatory signaling.
ABSTRACT Objectives To assess the safety and pharmacokinetics (PK) of single-dose subcutaneous (SC) sarilumab or tocilizumab SC ± methotrexate (MTX) and to assess the pharmacodynamics (PD) of sarilumab SC or tocilizumab SC monotherapy in Japanese rheumatoid arthritis (RA) patients. Methods TDU13402 was a randomized, double-blind, placebo-controlled, single-ascending dose Phase 1 study (NCT01850680). Twenty-four patients (6 per treatment group) received sarilumab 50, 100, or 200 mg plus MTX or placebo (2 per cohort) on Day (D) 1; PK and safety were assessed through D57. PDY14191 was a randomized, open-label, single-dose study (NCT02404558). Thirty patients (15 per arm) received sarilumab 150 mg or tocilizumab 162 mg on D1; PK, PD, and safety were assessed through D43. Results TDU13402: mean serum sarilumab exposure increased in a greater than dose proportional manner from 50 to 200 mg dose with no clinically meaningful increase in treatment-emergent adverse events (TEAEs). PDY14191: PK profiles of single-dose sarilumab 150 mg or tocilizumab 162 mg were similar; some numerical differences in PD profiles and TEAEs were observed. Neutrophil count decrease/neutropenia was the most frequently reported TEAE with sarilumab treatment in both studies. Conclusions PK, PD, and safety profiles of single-dose sarilumab SC with/without MTX were consistent with results anticipated in Japanese patients with RA.
